Manually operable means for modifying the action of an automatic control device



Dec. 6, 1955 M. w. CARLSON 2,726,299

MANUALLY OPERABLE MEANS FOR MODIFYING THE ACTION OF AN AUTOMATIC CONTROL DEVICE Filed June 28, 1954.

F121. 7 Q I Inventor: Morris William Carlson WM W His Attorney.

United States Patent Oi 2,726,299 Patented Dec. 6, 1955 MANUALLY OPERABLE MEANS FOR MODIFYING THE ACTION OF AN AUTOMATIQ CONTROL DEVICE Morris William Carlson, Morrison, lll., assignor to General Electric Company, a corporation of New York Application June 28, 1954, Serial No. 439,596

6 Claims. (Cl. 2llll138) This invention relates to thermostatic control devices of the type generally used in connection with domestic warm air furnaces, and more particularly to auxiliary means in association with such devices for modifying their operation.

Conventional domestic warm air furnace systems include, in addition to the burner and combustion chamber, a thermostat located in the area to be heated. The thermostat is generally arranged to start the burner responsive to the temperature in the area to be heated falling to a predetermined level. A fan for circulating warm air is arranged to be turned on either with the burner or when the temperature of the air in the furnace plenum chamber reaches a predetermined high level, the last of these two systems being generally considered preferable. The thermostat will normally turn off the burner when the temperature of the area to be heated has risen to the desired level. Again, the fan may be turned off with the burner or else kept running so as to exhaust the warm air from the furnace plenum chamber until the temperature therein has fallen to a predetermined low level, the latter of these two choices being generally considered preferable because of the economy achieved. Apparatus for achieving the preferred results described above is shown and described in Patent 2,633,517 issued March 31, 1953, to Ralph W. Gustafson, and in copending application Serial No. 405,952, filed January 25, 1954, filed by the applicant of the present application, both of these being assigned to the assignee of the present application.

Since such apparatus is wholly automatic, it is clear that when the temperature in the furnace plenum chamber is below the last-mentioned predetermined low level the fan circuit will be opened and the fan will not operate. However, during the warmer months of the year, when the burner will of course not be in operation, it is frequently desirable that it be possible to operate the fan alone so as to circulate cooling air throughout the area without regard to the action of the furnace system. Since the automatic means are expressly designed to prevent such an occurrence, it becomes desirable to include auxiliary means through which the action of the automatic means may be so modified that it is possible to operate the fan below the predetermined low temperature. Such auxiliary means should preferably be simple and economical to manufacture, easy to operate, and fully compatible with the structure of the automatic control so that there will be no interference when the burner is utilized to produce warm air.

It is, therefore, an object of this invention to provide a thermostatic control device having auxiliary means incorporating the desirable features set forth above.

Further objects and advantages of this invention will become apparent and the invention will be better understood by reference to the following description and the accompanying drawing, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

This invention, in its broadest aspects, provides externally operable means in combination with a control device. The control device includes a switch controlling a circuit, the contacts of the switch generally being actuated by a contact actuating member which preferably is normally biased outwardly, the circuit being closed when the member is in its normal biased position and being open when the member is pushed in. Movement of the contacts may be in response to any predetermined event, such as a particular temperature. The externally operable means is mounted so as to be movable to two positions. with a portion which in one position is close to the base of the contact actuating member so that an actuating member may push in the contact actuating member without interference. When the externally operable means is moved to its second position the portion is advanced to be in front of the contact actuating member so as to interfere with and prevent the action of the actuating member in moving the contact actuating member to open the circuit. Thus, when the externally operable means is in its second position, the circuit is maintained closed despite the fact that the predetermined level at which the circuit would normally be opened has been passed.

In the drawing, Figure l is a front view, partly in cross section and partly cut away, of 'an automatic control embodying the improved auxiliary means;

Figure 2 is a side view, partly in cross section and partly cut away, of the apparatus of Figure 1;

Figure 3 is an enlarged view of the improved auxiliary means of this invention in a first position; and

Figure 4 is an enlarged view of the improved auxiliary means of the invention in a second position.

Referring now to Figures 1 and 2 of the drawing, there is shown a thermostatic control device generally indicated by the numeral 1. This device comprises a helical bimetallic element 2 enclosed in a tubular housing 3 and having its outer end 4 connected to the outer end 5 of a shaft 6. Ordinarily housing member 3, bimetallic element 2, and end 5 of shaft member 6 extend into the warm air plenum of the furnace (not shown) through an opening in the wall thereof while enclosure 7 and the operating mechanism, generally identified as 8, enclosed therein are positioned on the exterior of the furnace. Tubular housing 3 is rigidly secured to the back wall 9 of enclosure 7 by holding lugs on tube 3 formed against the inside surface of enclosure back 9. The inner end 11 of helical bimetallic element 2 is also rigidly secured to the back wall 9 of the enclosure 7 by calibration adjusting screw 10 and connection 12. The shaft 6 extends through opening 13 in part 12 which is attached to back wall 9 of enclosure 7 and serves as a bearing for shaft 6. It will now be seen that with end 11 of helical bimetal element 2 firmly secured, changes in the temperature to which it is exposed will cause it either to coil itself up more tightly or to uncoil thus causing shaft 6 to rotate in one direction or the other dependent upon the direction and amount of temperature change.

Shaft 6 has three operating members, 14, 15 and 16 adjustably attached thereto so that the relative angular position of these members may be selectively changed; however, these members will normally move with shaft 6. The means of attachment of operating members 14, 15 and 16 to shaft 6 to provide this adjustable feature are more fully shown and described in the aforesaid Gustafson patent. Operating members 14, 1S and 16 are respectively provided with operating arms 17, 18 and 19. These operating armsextend at right angles to the operating members 14, 15 and 16, in the same direction as and parallel with shaft 6. Operating arm 19 is positioned so Part of the externally operable means is formed that at a predetermined temperature within the furnace plenum chamber shaft 6 will cause member 19 to depress a protruding part 2% of a switch 21 and thereby break the circuit (not shown) to the burner (not shown); this apparatus is more fully described in th aroresaid application by the present applicant and is not further discussed herein.

Another switch member 22 having an element 23 protruding from an embossed portion 51 of the switch is provided in order to control the circuit to the furnace fan (not shown). Switch 22 is preferably constructed so that when member 23 is in its normal protruding position the contacts are closed to permit t.e fan to operate and when member 23 is depressed the contacts are open to stop the fan. In order to actuate fan switch 22 a switch actuating member 24 is provided having its upper end 25 pivoted on a bracket 26. Bracket 26 is secured to the back wall 9 of enclosure 7 and is provided with upper extension 2'7. An overcenter spring 28 connects bracket extension 27 to cross bar 29 of actuating member 24 and it is thus seen that actuating member 24 will have two stable positions, a first position as shown in Figure l, and a second position which occurs when member 24 is moved to the left as explained below. The mid-portion 30 of switch actuating member 2 is arranged to engage actuating button 23 of fan switch 22 when the actuating member 24 is in its first position, thus moving the actuating button to its contacts open position. When the switch actuating member 24 is in its second position, that is, when member 24 has been moved to the left, switch actuating button 23 is allowed to return to its normal (contacts closed) position. Member 24 is provided with a curved lower portion 31 and is arranged so that at a predetermined high temperature arm 13 will be rotated by shaft 6 to move member 2 to the left and permit button 23 to close the contacts of switch 22. By the same token, at a predetermined low temperature level in the furnace plenum chamber member 17 will move to the right to cause actuating member 24 to force in button 23 thereby opening the contacts in switch 22. The foregoing explanation illustrates the workings of control device 1; in addition, this device is completely described in detail in the aforementioned copending application of the present applicant.

Referring now to all four figures of the drawing, the improved auxiliary fan control means will be described. An opening 32 is provided in top casing 33 to accommodate a member Member terminates in a p rt 35 which is designed for manual operation. Bracket 26, which has previously been described as being secured to back housing 9, has a leg 36 at right angles to the back housing. Member as is provided with a recessed bearing surface 37 by means of which member 34 is mounted on leg-36 of bracket 26. Leg 36 of the bracket is preferably provided with a groove 33 in order to accurately seat the member 34. It will now be seen that by means of this mounting, member 34 is placed in a position so that part 35 extends outside the control device and so that the member 34 may be pivoted about point 38. A spring member 39 having extensions 4% and 41 is slidably seated against the inner surface of housing part 33 by means of these extensions. A slot 42 is provided in spring 39 in order to accommodate the passage therethrough of member 34. The length of slot :2 is only slightly greater than the width of the section of member 3 which passes therethrough. Hence, spring member 39 moves each time member 34 is pivoted about point 353. The member 34 has a widened section i3 terminating in a point 44 against which the spring 39 is arranged to bear. This action of spring 39 tends to force the member 34 downwardly and the downward push is counteracted by the presence of part Bdcf bracket 26; therefore, the combination of the bracket and the spring maintains member 34 securely in place sothat it may not be displaced. it will, of course, be sen that spring 39 by its frictional engagement at 4-0 and 41 with cover member 33, will tend to maintain the member 34 in whichever of the positions shown in Figures 3 and 4 it is pivoted to. This effect is enhanced by the fact that the force of spring 39 against point 44 goes over-center with respect to pivot 33 when the member 34 is moved from one extreme position to the other. Member may be provided with a U-shaped recess as shown at 47, the bight of this recess being arranged so that it is either adjacent to or bearing against back housing member 9. The provision of this recess, in combination with the sides 50 of opening 32 in top casing 33, prevents member 34 from making undesirabl lateral and twisting movements.

it will be observed that member 34 terminates in a flange perpendicular to the remainder of the member. Referring particularly to Figure 2 of the drawing, it will it flange extends inwardly to a distance end 49 of flange overlaps arm 17 and but does not reach as far as the edge of the potion 51 on the casing of switch 22. Referring v particularly to Figures 3 and 4, it will be seen that when member 24 is in position to depress button 23 to disconnect the fan, the end of button 23 will, when pushed down to its full extent, be flush with the surface of the embossed portion 51 on the case of switch 22. It wiil further be observed that the height of the embossed portion 51 is at least equal to the thickness of flange 43. Thus, when member 3 9 is in the position shown in Figure 3 by dint of manual operation of part 35 to that position, flange i3 will be in such a position that member 24 may be actuated by arm 17 to depress button 23 without any interference whatsoever from flange 48. When member 35 is moved to the position shown in Figure 4, it will be observed that member 3 3 pivots about notch 38 so that flange is moved to the left beyond the normal outward position of button 22. Since flange 48 extends sufiiciently far, as at 49, to engage member 24-, it will be seen that when flange 48 is in the position shown in Figure 4, member 24 will be held to the left as shown. Flange 48 will, therefore, oppose the action of arm 17 when bimetallic element 2 causes arm 17 to move to the right against member 24. In this manner flange 43 may be so positioned as to prevent depression of button 23 and, consequently, the opening of the fan circuit by movement of arm 17 which normally occurs at a predetermined low emperature level. It will, of course, be understood that the frictional engagement of parts 40 and 41 of spring 39 with the inner surface of cover member 33, and the overcenter arrangement stated previously, provide a load which is in excess of the force from the movement of bimetallic element 2. Either the frictional engagement or the over center arrangement may be made such, if so desired, that the other of the two may be omitted.

When member 34 is moved to the position of Figure 3, its travel is limited by the combined action of side 52 of bearing surface 37 pressing against leg 36 of bracket 26, and by flange 43 pressing against the casing of switch 22. In this position, flange 48 will not prevent depression of button 23 by member 24. When member 34 is moved to the position of Figure 4-, its travel is limited by the end 53 of opening 32.

It will now be seen that, notwithstanding the entirely automatic operation of the fan including the automatic shutting off at the predetermined low temperature level, it is possible by means which are simple and economical to manufacture to prevent the shuttin off of the fan at will so that the fan may be operated irrespective of the temperature. it will further be seen that with the possible exception of extra part 35 which is, of course, purely optional, this effect is achieved by a single, easily formed piece of sheet metal in combination with a highly elementary type of spring. I wish it to be understood that this invention relates to the auxiliary means of negating the automatic control, and that the exact construction of the control itself, being covered by the aforesaid copending application of the present applicant, is tended to be covered herein.

While this invention has been explained by describing a particular embodiment thereof, it will be apparent that improvements and modifications may be made without departing from the scope of the invention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus having a switch and actuating means arranged to move toward and into engagement with said switch upon occurrence of a predetermined event, auxiliary means for preventing said engagement comprising a member movable to a position in which it is positioned between said switch and said actuating means thereby to prevent engagement of said switch.

2. In apparatus having a switch and actuating means arranged to move toward and into engagement with said switch upon occurrence of a predetermined event, auxiliary means for preventing said engagement comprising an elongated member having one end extending outside said apparatus, fulcrum means secured to said apparatus, said member being pivotable about said fulcrum at a point intermediate its ends, an arm extending from said member substantially at the other end thereof, said member being pivotable to two positions, said arm being positioned between said switch and said actuating means in one of said positions thereby to prevent engagement of not insaid switch and being positioned out of the path of movement of said actuating means in the other of said positions.

3. In apparatus having a switch with a member extending therefrom and means arranged to move toward and depress said extending member, said apparatus being enclosed ina housing having an opening, auxiliary means for selectively preventing said depressing comprising an elongated member having one end extending through said opening, fulcrum means secured to said housing, said elongated member having a bearing surface formed therein intermediate the ends and being arranged so that it will pivot about said fulcrum means to two positions, said elongated member being pivotable to two extreme positions through force applied to said end extending through said opening, an arm extending from said elongated member and positioned so that it extends into the path of said depressing means when said elongated member is in one of said positions thereby preventing said depressing means from depressing said extending member, said arm being movable to a position beyond the end of the path of said depressing means when said elongated member is moved to the other of said positions whereby said depressing means may depress said extending member without interference.

4. In apparatus having a switch with a member extending therefrom and means arranged to move toward and depress said extending member, said apparatus being enclosed in a housing having an opening, auxiliary means for selectively preventing said depressing comprising an elongated member having one end extending through said opening, fulcrum means secured to said housing, said elongated member having a bearing surface formed therein intermediate the ends and being arranged so that it will pivot about said fulcrum means to two positions, an arm extending from said elongated member and positioned so that it extends into the path of said depressing means when said elongated member is in one of said positions thereby preventing said depressing means for depressing said extending member, said arm being movable to a position beyond the end of the path of said depressing means when said elongated member is moved to the other of said positions whereby said depressing means may depress said extending member without interference, and means engaging said elongated member and said housing and arranged to maintain said member in the selected position.

5. In apparatus having a switch with a member extending therefrom and means arranged to move toward and depress said extending member, said apparatus being enclosed in a housing having an opening, auxiliary means for selectively preventing said depressing comprising an elongated member and having one end extending through said opening, fulcrum means secured to said housing, said elongated member having a bearing surface formed therein intermediate the ends and being arranged so that it will pivot about said fulcrum means to two positions, an arm extending from said elongated member and positioned so that it extends into the path of said depressing means when said elongated member is in one of said positions thereby preventing said depressing means from depressing said extending member, said arm being movable to a position beyond the end of the path of said depressing means when said elongated member is moved to the other of said positions whereby said depressing means may depress said extending member without interference, said elongated member having an enlarged section between said opening and said fulcrum means, and a leaf spring positioned between and bearing against said housing and said enlarged section thereby to maintain said member in the selected position.

6. In apparatus having a switch with a member extending therefrom and means arranged to move toward and depress said extending member, said apparatus being enclosed in a housing having an opening, auxiliary means for selectively preventing said depressing comprising an elongated member having one end extending through said opening, fulcrum means secured to said housing, said elongated member having a bearing surface formed therein intermediate the ends and being arranged so that it will pivot about said fulcrum means to two positions, an arm extending substantially perpendicularly from said elongated member and positioned so that it extends into the path of said depressing means when said elongated member is in one of said positions thereby preventing said depressing means from depressing and extending said member, said arm being movable to a position beyond the end of the path of said depressing means when said elongated member is moved to the other of said positions whereby said depressing means may depress said extending member without interference, said elongated member having an enlarged section between said opening and said fulcrum means, and a leaf spring positioned between said housing and said enlarged section, said spring having a substantially centrally located slot therein, said elongated member being arranged to pass through said slot whereby said spring is moved with said elongated member, said spring being arranged to bear against said enlarged section and against said housing on each side of said elongated member thereby to maintain the same in the selected position.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,035 Foster Aug. 24, 1937 2,247,195 Frank et a1. June 24, 1941 2,260,583 Rypinski Oct. 28, 1941 2,476,648 Zeller July 19, 1949 

